Integrated circuit devices and methods of forming the same are provided. Integrated circuit devices may include a channel region protruding from a substrate in a vertical direction, a first source/drain region, and a second source/drain region. The first source/drain region may vertically overlap the channel region. The first and second source/drain regions may contact a first portion and a second portion of the channel region, respectively, and a third portion of the channel region between the first and second portions may include a first channel region extending longitudinally in a first horizontal direction that is perpendicular to the vertical direction and a second channel region extending longitudinally in a second horizontal direction that is perpendicular to the vertical direction and traverses the first horizontal direction. The integrated circuit devices may also include a gate structure on opposing vertical sides of the channel region.